mount-tee-partition: add systemd service to format persist

QTEE requires a valid filesystem on the persist partition mounted at
`/var/lib/tee` to store encrypted data. If the persist partition is
unformatted, the mount fails and dependent services such as
qtee_supplicant cannot function.

Add a systemd oneshot service that checks for an existing filesystem on
the persist partition and formats it as ext4 when missing. The service
runs once during early boot, before var-lib-tee.mount, to ensure a valid
filesystem is available at `/var/lib/tee`, and disables itself after
successful execution.

Signed-off-by: Viswanath Kraleti <viswanath.kraleti@oss.qualcomm.com>

Author: vkraleti

recipes-bsp/partition/mount-tee-partition/format-tee-partition.service

@@ -0,0 +1,28 @@
+# Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+#
+# SPDX-License-Identifier: BSD-3-Clause-Clear
+
+[Unit]
+Description=Create ext4 filesystem on persist partition if missing
+Requires=dev-disk-by\x2dpartlabel-persist.device
+After=dev-disk-by\x2dpartlabel-persist.device
+ConditionPathExists=/dev/disk/by-partlabel/persist
+Before=var-lib-tee.mount
+Wants=var-lib-tee.mount
+ConditionPathIsMountPoint=!/var/lib/tee
+
+[Service]
+Type=oneshot
+ExecStart=/bin/sh -c '\
+  DEV=/dev/disk/by-partlabel/persist; \
+  if [ -n "$(/sbin/blkid -o value -s TYPE "$DEV" 2>/dev/null || true)" ]; then \
+    echo "$DEV already has a filesystem, skipping mkfs"; \
+    exit 0; \
+  fi; \
+  /sbin/mkfs.ext4 "$DEV" \
+'
+ExecStartPost=/bin/systemctl disable format-tee-partition.service
+RemainAfterExit=yes
+
+[Install]
+WantedBy=local-fs-pre.target

recipes-bsp/partition/mount-tee-partition_1.0.bb

@@ -4,7 +4,10 @@ encryped data and support security functions"
 LICENSE = "BSD-3-Clause-Clear"
 LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/BSD-3-Clause-Clear;md5=7a434440b651f4a472ca93716d01033a"
 
-SRC_URI = "file://var-lib-tee.mount"
+SRC_URI = " \
+    file://var-lib-tee.mount \
+    file://format-tee-partition.service \
+"
 
 inherit allarch features_check systemd
 REQUIRED_DISTRO_FEATURES = "systemd"
@@ -18,8 +21,10 @@ do_compile[noexec] = "1"
 do_install() {
     install -Dm 0644 ${UNPACKDIR}/var-lib-tee.mount \
             ${D}${systemd_unitdir}/system/var-lib-tee.mount
+    install -Dm 0644 ${UNPACKDIR}/format-tee-partition.service \
+          ${D}${systemd_unitdir}/system/format-tee-partition.service
 }
 
 PACKAGES = "${PN}"
 
-SYSTEMD_SERVICE:${PN} = "var-lib-tee.mount"
+SYSTEMD_SERVICE:${PN} = "var-lib-tee.mount format-tee-partition.service"